A Miami police officer who recently resigned while under investigation pleaded guilty to extortion charges Friday in federal court, the latest embarrassment for the city’s embattled police department.

Harold James, 29, surrendered to authorities Thursday on charges related to a broad FBI corruption probe that began last year with an investigation of a police-protection racket for a sports-betting ring operating out of a Liberty City barbershop.

James, an eight-year veteran, was charged with two counts of extortion for allegedly providing protection for “the cashing of fraudulent checks” in exchange for cash payments, according to court records.

James allegedly provided the protection to a courier engaging in “illegal activity’’ in April and May at a business behind a Sunoco gas station at Northwest 79th Street and Seventh Avenue in Liberty City, where purported tax refund checks were being cashed.

James made his first appearance in federal court Thursday, entering an initial not guilty plea, and was released on a $75,000 bond, according to his defense attorney Tony Moss. But the defendant had a change-of-plea hearing Friday before U.S. District Judge Robert Scola.

Assistant U.S. Attorney Robin Waugh is seeking to seize $800 from James that she says he pocketed from the alleged protection racket.

The FBI, which has been working with Miami police internal affairs investigators since the Liberty City gambling operation was shut down in March of last year, is expected to make more arrests.

James became the second Miami officer criminally charged in as many days. In an unrelated case, authorities arrested Officer Luis Hernandez, 27, Wednesday and charged him with armed kidnapping and sexual battery by a law enforcement officer. Also Wednesday, the department fired an officer, Reynaldo Goyos, for shooting and killing an unarmed motorist two years ago.

James last worked in the Model City neighborhood before he resigned in November, city records show. He generally received above-average performance evaluations, and he received nine commendations over his career. James was reprimanded seven times, mostly for traffic accidents or failing to appear for court hearings, records show.

In January, fellow Miami Officer Nathaniel Dauphin became the first of several cops swept up in the anti-corruption dragnet of the city’s besieged police department.

Dauphin, 41, allegedly helped organize the protection racket for the Liberty City sports-betting operation. He pleaded not guilty to a single charge of extortion conspiracy, alleging that he “protected and facilitated illegal activity — gambling — in exchange for receipts of cash payments.’’

Dauphin, a police officer since 1996, was allegedly paid $5,000, according to the charge.

James and Dauphin are among at least 10 Miami police officers expected to soon face federal criminal charges or internal discipline related to the gambling protection scheme and other criminal activity, The Miami Herald has learned.

Seven of the officers under scrutiny, including James, have already resigned or been relieved of duty in recent weeks, according to sources close to the probe.

The targeted officers, who worked in the Model City substation, are suspected of providing off-the-books protection and frequenting the Player’s Choice Barber Shop, 6301 NW Sixth Ave.

Also relieved of duty are officers Malinsky Bazile, 27, Vital Frederick, 26, and Angel Mercado, 29, who are suspected of other criminal activity unrelated to the alleged protection racket. All continue to receive pay while the investigation continues.

In December, Officer Lashunda Hodge, 31, was relieved of duty with pay as part of the protection-detail probe. At least three other officers are facing scrutiny, too: Hodge’s roommate, Kenya Crocker, 39; Dauphin’s girlfriend, Carol Vargas, 39, and Darryl Bryant, 51, according to sources familiar with the case.